That's a lot of code - someone might work on it, but generally you can't expect someone to do all that work for free. Check out the forum guidelines on posting code as detailed in the charter: [webmasterworld.com...]

The main thing you need to do is boil this down to a test case: the minimum amount of code necessary to demonstrate the problem. So you have font rules and things like that in your code.

Make a live page and load it in your browser and just start deleting code until the problem goes away or until you have the minimum code to show the dropdown that's having problems.

If the problem has goes away at some point, you've found your problem. If it doesn't post just the code necessary to display the problem dropdown and maybe someone will help with that.

At a cursory glance you've got at least three separate items (< or first child; min-/max-height; center) that are known not to work in MSIE <= some number. So you may well have more than one unrelated problem.